Hydraulic power converter



April 27, 1954 F. BERRY '2,676,462

HYDRAULIC POWER CONVERTER Filed May 27, 1952 El@ 1I FRAN/f BERRY Y 7?@ WATTRNEYS Patented Apr. 27, 1954 UNITED if 2,676,462 HYDRAULIC POWERCNVERTER 'Frank Berry, Corinth, Miss.,

Steel Cox-por Iron and a corporation of Pennsy assigner to Oliver ation,Pittsburgh, Pa., lvania 8 Claims. l The invention relates to hydraulicpower converters.

SUMMARY According to my invention, Vtwo rotary hydraulic pump devices.mechanically driven from any source of rotary power, Aare'hydraulically coupled to a reciprocatory hydraulic motor in alternatephase relationship so that 'each pump works onehalf kof the time, and sothat during the time each pump is idling it is acting as a valve toby-pass liquid between the motor and the pump that is working; and VIarrange a by-pass relief valve around the motor, this valve beingadjustable to operate at a predetermined pressure to bring, and keep,the motor automatically in phase with the pump devices. In practice, Imake the two pump devices as an integral unitfdri-ven from a commonpower source.

In my preferred construction I also provide a series of Foy-passchannels between each rotary pump cylinder andthe iluidinlet tosuchcylinder, and a valve arranged toopen or close one -or more of suchby-pass channels sequentially to predetermine the length of stroke ofthe reciprocatory motor piston.

It is va particular object of my invention to provide a direct hydraulicdrive between the rotary pumps and reciprocatory motor withoutintervening valves of any kind, the lonly basic valve requirement beingthe auxiliary by-pass valve for automatic regulation -of the phaserelationship between ythe rotary and reciprocatory elements. rI'here isno valve between the pump pistons and the motor piston.

Other objects and advantages -of my invention will appear as thedescription proceeds.

DESCRIPTION The drawing illustrates my invention in what I presentlyconsider to be its best Aform and arrangement. 'The two pump devices inthis case are made as an integral unit which, together with thereciprocatory motor, are shown in cross-section taken at the centerlineof the cylinders, with the pistons, piston rod, piston rotors and rotaryabutment shown in elevation. For simplicity of illustration the fluidconduits and the cooler unit likewise are shown in elevation.

I prefer to employ a rotary pump assembly of a kind which is generallyknown in the art as the rotary abutment type of unit. Details of theconstruction and operation of this type of unit are well known. See, forexample, my prior patents, Nos. 2,464,481and 2,536,486. A form of thisunit which is particular-ly adapted 'for use in conjunction with mypresent invention is shown an i described in my prior patent No.2,614,503, known commercially as a pancake type unit in which there aretwo annular pump cylinders arranged in a common plane with the rotaryabutment va ve between so as to act as a valve `for the pistons of bothcylinders. However, this is incidental to the operation of my presentinvention which in essence requires `the use of two rotary pump devicesdriven from a common source of rotary power in such 'phase relationshipthat in operation each spells the other, i. ewone pumps while the otheridles. and vice versa.

The pump assembly Referring to the drawing, the rotary pump assembly isindicated generally by reference P and the reciprocatory motor byreference M. The pump assembly comprises a casing l in which are formeda pair of annular pump-cylinder 2 and 3, having fluid inlets -4 and -5and uid voutlets t and respectively.

Definition- The terms inletsWand outlets as used herein and in theappended claims are employed primarily with reference to the passagewaysor ports which'act as inlets or outlets for the hydraulic fluid duringthe power `stroke of the pump. Since, as I shall describe, the huid flowthrough each pump Vreverses during that half of the cycle in which thatpump is idling, it will be understood that the fiuid then nows inthrough the outlet and out through the inlet This secondary function ofthe inlets and outlets need give rise to no confusion so long as it 'isremembered that I use the terms V(l) 'to "designate 'the passagesirrespective of their function, and (2) to indicate the primary functionof those 1passages during the power stroke of the pump.

Piston rotors 8 and 9 with pistons lo and il are arranged in therespective annular cylinders 2 and 3. 'Ihe pistons may be integral with'the rotors, and the rotors may be integral with their shafts I2, i3 oraiixed thereto. The rotors are driven from a rotary power source such asan electric motor or internal combustion engine.

In the preferred construction shown, a rotary abutment it having' arecess I5 to clear veach piston as it passes the abutment is arrangedbetween the two annular pump cylinders '2 and 3. Shaft l5 ci the rotaryabutment is geared to lthe shafts l2 and i3 of the pumps ina gear ratioof 1:1. The prime mover 'for driving vthe pumps may be coupled to shaftit* of the rotary abutment or to the shaft I 2 vor 'i3 `-of either :ofthe pump rotors as fdesired. This .concludes the general description ofthe annular' pumps. The volume or stroke control feature of these pumpswill be described later, as this feature can best be understoodfollowing a description of the reciprocatory hydraulic motor and themanner in which the latter is driven from the pumps.

'The hydraulic motor The reciprocatory hydraulic motor comprises in itsgeneral arrangement a casing Il in which is formed a cylinder I8carrying a fluid driven reciprocatory piston I9. A rod 2t extends fromthe piston to a reciprocatory power take-ofi (not shown). Rod has asection 2l forming a plunger reciprocating in an auxiliary cylinder 22communicating with motor cylinder i8. In the construction speciiicallyillustrated, rod 2e is formed as an integral extension of the piston i9and is of stepped construction at each side of the piston so as toprovide plunger 2i at each side thereof, and there are auxiliarycylinders 22 for each of the plungers formed in end casing members 23bolted to the main casing il. Suitable glands or O rings 2d are receivedin recesses in the ends of the auxiliary cylinders to afford a sealwhere the reciprocatory rod 2u extends through the end casing members.Stops 2.5 on the rod limit the extent of travel of the piston I9 ineither direction.

Inclined channels 4l in each oi the plungers 2l provide for variableflow of the hydraulic fluid between motor cylinder I8 and the respectiveauxiliary cylinders 22. Because the channels are inclined, and thereforeprogressively smaller in cross-section in the direction toward thepiston I9, the ow of the hydraulic fluid from auxiliary cylinder 22 intothe main motor cylinder I8 becomes more and more restricted as theplunger ZI moves into the auxiliary cylinder. This restricting or"pinching off of the now provides a shock control which cushions theaction of piston I9 as it reaches the end of its stroke and reversesdirection. Thus this shock control feature comprises the provision of apassageway (il of variable cross-section (progressively greatercross-section in a direction away from the piston) so that liquidflowing from the auxiliary cylinder 22 into the motor cylinder i8 mustpass through a channel which becomes progressively smaller as the pistonI9 reaches the end of its stroke.

Automatic timing means A by-pass channel 25 connects the two ends of themotor cylinder together and a valve 2l in this channel is operable inresponse to a predetermined uid pressure in either end of the motorcylinder to open the channel 2G and by-pass liquid until the motorpiston I9 reaches the end of its stroke. Valve 2l is received in boresof casing Il and carries at its upper end a piston 28 received in acylinder 29 formed in an extension 3? c1 the casing. A passage SIconnects the inner end of the valve bore with the by-pass channel 2S atone side of the valve 2l and passage 32 connects the inner end ofcylinder 29 with the by-pass channel 25 at the other side oi the valve.The valve 2l is urged inwardly toward its closed position by means of acompression spring the initial compression of which is adjusted by handscrew Sli threaded in the end cap 35 of cylinder 29. Operation of themotor and its automatic timing device can best be considered after adescription of the hydraulic connections between the pumps and motorwhich here follows:

It will be remembered that there is a pair of uid inlets 4 and 5, and apair of fluid outlets li and l, in each case one for each pump cylinder.In the preferred construction illustrated, inlets l and 5 are connectedtogether by fluid conduit 3%, outlet e is connected to one end of motorcylinder I8 by conduit 31, and outlet 'i is connected to the other endof the motor cylinder by conduit 3d. An alternative arrangement which isequally satisfactory is to connect the outlets 6 and I together andconnect the inlets 4 and 5 to the respective ends of the motor cylinderI8, the arrangement being otherwise exactly as shown in the drawing. Atany convenient point in the hydraulic system a cooler 39 of conventionalconstruction may be installed. Oil or other operating fluid isintroduced, and from time to time replenished as need be, through asuitable connection Mi. Also it is desirable to provide a spring-loadedaccumulator 4I communicating with one of the iluid conduits. Thisconsists of a simple cylinder device 42 in which is a piston d3,spring-pressed by compression element M the initial compression of whichis adjustable by means of a thumb screw l5 threaded in the end cap 46 ofcylinder casing 42.

Having regard to the alternative arrangements of the uid connections, itwill be observed that selected pairs of the fluid inlets 4, and outlets6, i are connected by fluid conduits as follows: one pair connectedtogether, one member of the other pair connected to one end oi the motorcylinder and the other member of said other pair connected to the otherend of the motor cylinder.

Operation of the converter and automatic timer Operation will rst beconsidered without regard to the stroke control mechanism which remainsto be described. It has been stated that the two rotary pump devices arein such phase relationship that in operation each spells the other, i.e. one pumps while the other idles, and vice versa. Flow of thehydraulic fluid through the several conduits is indicated in the drawingby means of arrows. lThere are two sets of these arrows, one in whichthe stems of the arrows are represented by full lines and the other inwhich the stems are dotted. The full line arrows indicate the directionof now when the lower one of the two rotary pump devices is pumping andthe upper one idling, i. e. when piston Ii is in its power stroke incylinder 3 of the lower pump. The dotted line arrows indicate thedirection o flow when the upper pump is working and the lower pumpidling. Similarly the full line arrow superimposed on the left-handplunger ZI of the hydraulic motor M indicates the direction of movementof the motor piston assembly when the lower pump is operating in itspower stroke, and the dotted line arrow superimposed on the right-handplunger 2| indicates the direction oi movement of the motor pistonassembly when the upper pump is operating in its power stroke. With theposition of the movable parts of the pumps as shown in the drawing, thepiston Il of the lower pump is beginning its power stroke and the pistonle of the upper pump is beginning to idle. During the power stroke ofthe lower pump, liquid is discharged under pressure from outlet l, flowsthrough conduit 38 and moves motor piston i9 to the left in thedirection of the full line arrow superimposed on left-hand plunger ZI.On what is then the low pressure side of motor piston i9, i. e. to theleft thereof, the low pressure liquid is withdrawn through conduit 37,thence through the idling upper pump, conduit 36, cooler 39,. and nallyis drawn into the pump casing at theV l'ow pressure side of.' pistonII".v

As the pistonl of the: lower pump. reaches the end. of its power strokeand piston Iii of the upper pump the beginning of its power stroke, owis reversed to the direction indicated by the dotted line arrows.throughout, and motor piston I9 is moved in the direction of the dottedline arrow superimposed on plunger 2| at the right of the motor pistonassembly. Thus the lower pump moves piston I@ to the left, thereafterthe upper pump moves it back. to the right, and so on. This isaccomplished entirely without the use of valves between the pump pistonsand the motor piston.

The manner in which the motor is timed automatically to. bring itintoproper phase relationship with the pumps will now be described. Letus assume the existence of a temporary condition under which the motorand pumps are slightly out of phase so that, for example, piston I9reaches the end of one of its strokes before pressure is reversed by thepumps. In this case excessive pressure will be built up at one end ofthe motor cylinder. Suppose the case where piston il of the lowerl pumpis supplying fluid te the motor to drive motor piston I9 tothe left, i.e. in the direction of the full line arrow superimposed on left-handplunger 2|. Suppose further that motor piston I9 has reached the limitof its leftward-moving stroke at a moment when piston I I of the lowerpump has not reached the end of its pumping stroke and is thereforecontinuing' to supply iiuid to the right-hand end of the motor cylinderI8. Under these conditions further movement of pump piston I I willbuild up excessive pressure in the right-hand end of motor cylinder I8.When this pressure has reached a predetermined amount, valve 2l of theautomatic timer is lifted upward-ly by means of the pressurecommunicated through the passage 3l or" the timer. This permits acertain amount of the hydraulic uid to flow through by-pass channel 2Bof the timer until pump piston I I has reached the limit of itsleftward-moving stroke. Valve 2l will then close under the action ofcompression spring 33. At this point piston i9 will be in proper phaserelationship to the piston and the pumps. That is, piston I 9 is at theend of its stroke substantially at the moment that pressure is reversedby the pumps.

Similarly when the pressure to the left of motor piston I9 reaches apredetermined amount, this pressure will be communicated via passage 32ci the timer to the underside of valve piston 23, again raising thevalve and allowing a certain amount of the hydraulic fluid to passthrough bypass channel 2G to the other side of the motor cylinder.Again, when the piston It has reached the end of its stroke, and theproper phase relationship has been restored, valve il willclose underthe action of the compression spring 33. The proper pressure balance inthe timer is obtained through adjustment of the hand screw 34 toincrease or decrease the force exerted by spring as may be required.

The stroke control mechanism yifie volume or stroke control featurereferred to at the end of the preceding description of the pump assemblywill now be described. My preierred form of stroke control mechanismcomprises a valve 48 for each of the pumps, these valves beingadjustable to control by-pass channels between the respective annularpump cylinders and the inlets or low pressure sides of the pumps. Thevalves for each ofthe two pumps may be of the same construction so thedescription will proceed in the. singular. Valve d8 comprises a hollowcylinder or sleeve movable axially in valve. cylinder 49 formedin. pumpcasing I, the casing having an extension `Eil' forming the outer end ofthis cylinder. A series of Icy-pass channels 5I, 52, 53, 54, 55 isprovided between annular pump cylinder 3 and the iiuid. inletY 5 to saidis arranged to open and close these. lay-pass. channels. sequentially topredetermine the length of stroke of' the reciprocatory motor piston I3.For this adjustment4 I. provide a hand screw 5B threaded in the end cap.5? of cylinder '59. The. central portion 58' of hand screw 56 is: sealedat the end of cylinder il? as by means of a suitable packing or O ring5S carried in a recess of the end cap 5l. A reduced portion 68' at theinner end of the adjusting screw 5i; passes through the center bore Elof valve its with suiiicient clearance to allow the flow of hydraulicfluid from one side to the other of valve 48- as. it is being adjusted.Transverse channels 62 at each end of valve 48 provide communicationbetween the center bore 6i of the valve and the respective ends. ofvalve cylinder t9. Adjusting screw 56 is rotatable with respect to valveet but restricted against' endwise movement with respect thereto bymeans of' a washer 63 and suitable fastening pin therefor.

The stroke control valves. for the two pumps are adjusted together to.ythe same respective positions. As shown both of them block all five ofthe by-pass channels: 5I to 55 inclusive. Both may be adjusted to openonly by-pass channel 5i by retracting them untilv the inner ends ofvalve cylinders 'i5 are moved: outwardly to an extent which permitsdirect communication from the respective pump cylinders through channels5i to the inner ends of valve cylinders ee which are in communicationwith the inlets il and 5 respectively via openings till. it is of coursepossible to link the. two adjusting screws 5E together for simultaneousadjustment or setting, or if preferred they maybe linked togetherhydraulically by any well-known means, in either case assuring that theeffective stroke of each pump will be equal so as to produce the sameextent of movement of the motor piston I9 in each direction.

Operation of the stroke control mechanism With the stroke controlmechanism, the general operation-of the converter and automatic timerremains as described' hereinabove, if the valves i3 are adjusted to theposition shown in the drawing, operation is exactly the same as thoughthere were no stroke control mechanism provided. Therefore it will beunderstood that if a variable stroke is not desired, this mechanism maysimply be omitted. Thus with the valves i8 in the position shown, themaximum volume of the pump discharge, and therefore maximum stroke ofthe motor, are obtained. if a shorter stroke is desired, valves i8` areretracted by .means of adjusting screws 5S to provide ccmrnunicati'onthrough passages 5i to the inlets l and 5. With this adjustment andconsidering that the lower` pump is enteringv its power stroke, thepumping action of piston I! is modified by reason of the fact that someof the hydraulic uid ahead of the piston iiows through passage 5I backaround to the low pressure side of the piston. 'I'his has the eiect ofreducing the total discharge of hydraulic i'luid from the lower pumpduring its complete working stroke. Thereafter the piston I9 is moved tothe left as before, but to a shorter distance. Similarly when the' upperpump begins its power stroke, uid is by-passed` through its channelpassage. vbackaround to the low pressure side of piston 16,'reducing thelength of the return strokeof piston I9 to the right.

Further'retraction ofvalves 48 to sequentially place additionalpassages52', 53 etc. into communication with low pressure sides of therespective pistons further reduces the working stroke of motor pistonI9. When the valves lili are withdrawn to the limit' of theiradjustment, all five by-pass channels 5| to 55 are placed 'incommunication with the low pressure side of the respective pistons,substantially reducing the volume of fluid pumped during a completework-V ing stroke of the pumps, and further reducing the stroke of thereciprocatory hydraulic motor M.

My hydraulic power converter is useful for a variety of applications,indeed for almost any oase in which it is desired to have simple andpositive hydraulic means for converting rotary power` to reciprocatorypower as, forfexample, in

industrial machines having reciprocating'tcols driven by electricmotors, such as punch'presses, Shapers, and in farm machinery, such asmowing machines, shakers, harvesting machines, etc. The invention alsohas wide application in min ing and oil industries or whereverreciprocating pump elements are to be operated from a rotary powersource.

The terms and expressions which I have em ployed are used in adescriptive and not a limit-- ing sense, and I have no intention ofexcluding such equivalents of the invention described, or of portionsthereof, as fall within the purview of the claims.

I claim:

1. A hydraulic power converter for converting rotary motion toreciprooatory motion compris ing a pair of annular pump cylinders eachwith a fluid inlet and a fluid outlet so that there is a pair of fluidinlets and a pair of fluid outlets, piston rotors with pistons in theannular cylinders, said rotors driven from a rotary power. source, arotary abutment having a recess to clear each piston as it passes theabutment, a motor cylinder and a piston therein, a rod extending fromthe reciprocatory piston to a reciprocatory power take-oil, selectedpairs of said fluid inlets and outlets being connected by fluid conduitsas follows: one pair connected together, one member of the other pairconnected to one end of the motor cylinder and the other member of saidother pair connected to the other end of the motor cylinder', the actionof the pistons in the two pump cylinders being timed as follows: onepiston completing its power stroke substantially at the moment that theother piston begins its power stroke, and vice versa, and means forautomatically timing the action of the pumps to the action of the motor,said means comprising a by-pass channel connectingr the'two ends of themotor cylinder together and a valve in said channel responsive to apredetermined fluid pressure in either end of the-motorv cylinder toopen said channel and by-pass liquid until the motorpiston reaches theend of its stroke.`

fluid-driven reciprocatoryl i 2. A'hydrau'lic power converter as deiinedby claim vl in which saidvalve' is 'adjusted to said predetermined fluidpressure by adjusting .the pre-compression of the spring which normallyholds the valve in closed position.

3. A hydraulic power converter as defined by claim 1 in which said rodextending from the reciprocatory piston has a section forming a plungerreciprocating in' an auxiliary cylinder communicating with said motorcylinder through a passageway of variable cross-section so that liquidflowing from the auxiliary cylinder into themotor cylinder must passthrough a channel which becomes progressively smaller as the pistonnears the end of its stroke.

Il. A hydraulic power converter as dened by claim 1 in which said rodextending from the reciprocatory piston hasv plunger sections reciprolcating in auxiliary cylinders at either end of the motor cylinder, saidplunger sections having tapered channels therein of progressivelygreater cross-section in a direction away from the piston.

`5. A hydraulic power converter as defined by claim 1 in which alay-pass channel is provided between each annular cylinder and the fluidinlet to said cylinder, and a valve for opening and closing said by-passchannels to predetermine the length of stroke of the reciprocatory motorpiston.

6. A hydraulic power converter as defined by claim l in which a seriesof by-pass channels is provided between each annular cylinder and thefiuid inlet to said cylinder, and a valve arranged to open and closesaid by-pass channels sequentially to predetermine the length of strokeof the reciprocatory motor piston.

7. In combination, two rotory hydraulic pump devices mechanically drivenfrom asource of rotary power, a' reciprocatory hydraulic motoralternately driven'by the high pressure fluid discharge from first voneof said pump devices and then the other,.with the low pressure iiuiddischarge from said motor being returned to the intake of first one pumpdevice and then the other, and means for automatically timing the actionof the pump devices to the action of the motor comprising a oy-passchannel in the motor and a valve in said channel responsive to apredetermined duid pressure in the motor.

3. In combination, two rotary hydraulic pumps hydraulically connected toa reciprocatory hydraulic motor in alternate phase relationship so thateach pump is effective to discharge liquid under pressure during onlyone half of each complete revolution of the pump rotor and so thatduring the time each pump is idling itis acting as a by-pass valve, anda by-pass relief valve arranged in a channel between the ends of themotor operable at a predetermined pressure to keep the motorautomatically in phase with the two pumps.

References Cited in the iile of this patent UNITED STATES PATENTS NumberName Date 1,485,414 Junkers Mar. fl, 1924 1,949,723 Kotelevtseff Mar. 6,1934 2,155,421 Kenyon et al. Apr. 25, 1939 2,246,461 Cannon, Jr 'June17, 1941 2,282,977 Mast May 12, 194:2

